How many moles are present in 16.2 g of lead?

Hey there!

The pH of a weak base (in this case, pyridine is a weak base) is calculated by using the weak base equation, and then solving it.

C5H5N; Kb= 1.7 x 10⁻⁹

pH = -log [H⁺]

we can also say that pH = 14 + log [OH⁻]

Plugging into the weak base equation, we know that Kb = [OH⁻][BH⁺] / [B]

This can be solved using an ice chart, which will then simplify to :

Kb = [x][x] / [0.50-x]

We can assume that x is very small in comparison to the 0.5 , so we consider it zero.

Then plug in and solve for x.  1.79 *10-9 = x² / 0.5

x = 2.992 * 10⁻⁵

ince X is equal to the [OH⁻] concentration, we can plug it into the second pH equation, and get the pH!

pH = 14+ log 2.99 * 10⁻⁵

pH = 9.48

Hope that helps!

The pH of a 0.65 M solution of pyridine (C₅H₅N) is 9.52.  

The equation for the protonation of the base pyridine is the following:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻   (1)

The constant of the above reaction is:

[tex] K_{b} = \frac{[C_{5}H_{5}NH^{+}][OH^{-}]}{[C_{5}H_{5}N]} = 1.7 \cdot 10^{-9} [/tex]    (2)

To calculate the pH of the solution we need to use the following equation:

[tex] pH + pOH = 14 [/tex]      

[tex] pH = 14 - pOH = 14 - (-log[OH^{-}]) = 14 + log[OH^{-}] [/tex]   (3)

So, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):

C₅H₅N  +  H₂O  ⇄  C₅H₅NH⁺  +  OH⁻

0.65 - x                          x              x

After entering the values of [C₅H₅N] = 0.65-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:

[tex] 1.7 \cdot 10^{-9} = \frac{[C_{5}H_{5}NH^{+}][OH^{-}]}{[C_{5}H_{5}N]} = \frac{x*x}{0.65 - x} [/tex]  

[tex] 1.7 \cdot 10^{-9}(0.65 - x) - x^{2} = 0 [/tex]  

Solving the above quadratic equation for x, we have:

[tex] x_{1} = -3.32 \cdot 10^{-5} M [/tex]

[tex] x_{2} = 3.32 \cdot 10^{-5} M [/tex]        

We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into equation (3):

[tex] pH = 14 + log[OH^{-}] = 14 + log(3.32 \cdot 10^{-5}) = 9.52 [/tex]  

Therefore, the pH of the solution of pyridine is 9.52.

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I hope it helps you!    

The number  of hydrogen atoms that are in 7.80 moles of ammonium sulfide are  3.756 x 10^25  atoms

calculation

Step  1:  calculate  the  moles of H  in  (NH4)2S

 since there are 8 atoms of  H in (NH4)2S  the moles of

   H =  8 x7.80 =  62.4  mole

 Step  2: use of Avogadro's law  constant  to  determine the number  of  H atom

          that is 1 mole = 6.02 x10^23 atoms

                     62.4 moles=?  atoms

= [ 62.4  x 6.02 x10^23]/  1 mole= 3.756  x10^25    atoms

Answer: There are [tex]3.75 \times 10^{25}[/tex] number of H atoms in 7.80 mol of ammonium sulfide.

Explanation:

The formula of ammonium sulfide is [tex](NH_{4})_{2}S[/tex].

There are 2 nitrogen atoms, 8 hydrogen atoms and 1 sulfur atom in one molecule of ammonium sulfide.

Calculate moles of hydrogen atoms as follows.

              [tex]8 \times 7.80[/tex] = 62.4

According to Avogadro's number 1 mole contains [tex]6.022 \times 10^{23} atoms[/tex]

Therefore, calculate number of H atoms as follows.

               [tex]62.4 \times 6.022 \times 10^{23}[/tex]

             = [tex]375.77 \times 10^{23}[/tex]

             = [tex]3.75 \times 10^{25}[/tex]

Thus, there are [tex]3.75 \times 10^{25}[/tex] number of H atoms in 7.80 mol of ammonium sulfide.

Is Does not have a Coefficient so it would be No

The correct answer is B. Lindsay measures the sizes of the craters on the Moon, is the best description of a person doing science.

Science is the practical and intellectual pursuit of the understanding of the physical and natural world that surrounds us. It involves a systematic study: observation,  experimentation, data analysis, discussion and conclusion. Science is the human effort to gather knowledge about the universe.

Answer:

B.

Explanation:

A longer lifespan typically implies a higher chance of producing offspring because it provides a larger timeframe for successful reproduction. Organisms with extended lifespans have more opportunities to reproduce and can therefore often result in a larger overall number of offspring.

In the context of biological evolution, a longer life span generally signifies a higher chance of producing offspring. This is primarily because an organism with a longer life span has a longer period of reproductive viability, i.e., the timespan within which it can reproduce successfully. This increased amount of time for possible reproduction results in more opportunities to produce offspring, thus potentially leading to a larger overall number of offspring throughout the organism's lifetime.

Furthermore, this concept of a longer life span equating to more offspring is often seen in organisms such as turtles and many species of trees. These organisms live for many decades, or even centuries, and during this extended lifespan, they continue to reproduce, which increases their chances of having more offspring compared to organisms with shorter life spans.

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0.01631973355 is your answer. Have a great day and hope this helps!!!

To determine the moles of water lost when 0.294 grams evaporated, divide the mass by the molar mass of water, which is 18.015 g/mol, yielding approximately 0.0163 moles.

To find out how many moles of water were lost when 0.294 grams of water evaporated, you can use the molar mass of water. The molar mass of water (H₂O) is 18.015 g/mol. Therefore, you can calculate the number of moles by dividing the mass of the evaporated water by the molar mass of water.

Mass of evaporated water = 0.294 grams

Molar mass of water (H₂O) = 18.015 g/mol

Number of moles = Mass of water / Molar mass of water

Number of moles = 0.294 g / 18.015 g/mol

Number of moles = 0.0163 moles (approximately)

Therefore, 0.294 grams of water corresponds to approximately 0.0163 moles.

I believe an interaction between the biosphere and the atmosphere would be precipitation. Respiration is the process of breathing, and crystallization is the process of, well, crystallizing. :)

Answer: Apple juice is a homogeneous mixture.

Explanation:

There are two types of mixtures:

Apple juice is a homogeneous mixture because the juice appears uniform throughout and no phases between the particles is seen.

Hence, apple juice is a homogeneous mixture.

Apple juice is a homogeneous mixture, as its composition is uniform throughout, much like a commercial sports drink. This contrasts with heterogeneous mixtures like oil and vinegar salad dressing which have varying compositions.

Apple juice is considered a homogeneous mixture, also known as a solution. This type of mixture consists of substances with a composition that is uniform throughout. To illustrate, consider a commercial sports drink, another example of a homogeneous mixture. Its composition is the same in every part of the drink, just like how apple juice has a uniform consistency and taste throughout, irrespective of where you sample it from within the jug or glass. This is unlike a heterogeneous mixture, where the composition varies from point to point, like in oil and vinegar salad dressing.

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Hey there!

In a scientific experiment, there are three types of variables: dependent, independent, and control.

Independent variables are the variables that are changed and doesn't depend on another.

Dependent variables are the variables that are depending on the independent variable. When the independent variable changes, it affects the dependent variable.

Control variables are the variables that are kept the same throughout the entire experiment. These don't change at all.

Hope this helps!

Answer:- D.  [tex]Li_2CO_3(aq)+FeCl_2(aq)\rightarrow 2LiCl(aq)+FeCO_3(s)[/tex]

Explanations:- In chemical equations, (aq) stands for aqueous, (l) stands for liquid, (g) stands for gas and (s) stands for solid. In double replacement reactions, (aq) means soluble and (s) means insoluble that is precipitate.

Looking at all the equations, it is only the last equation that has a solid product and so this is the only precipitation reaction. A precipitate for Iron(II)carbonate is formed in it.

Answer:

The correct answer is

D.  Li2CO3(aq) + FeCl2(aq) → 2LiCl(aq) + FeCO3(s)

The volume of water measured using the graduated cylinder is not exactly identical identical to the volume calculated.

Calculated volume is theoretical value calculated from the density and mass of water.

But volume measured in cylinder can contain the personal error of individual.

Because in graduated cylinder volume is measured in a specific way that is:

Answer:

has 17 electrons

Explanation:

Chlorine is a halogen that belongs to the 17th group on the periodic table. Chlorine has an atomic number of 17. The atomic number of elements is used in placing and locating elements on the periodic table. In fact, the periodic arrangements of elements is as a result of their atomic numbers.

The atomic number is the number of protons in an atom. This number is the same as the number of electrons in a neutral atom that has not gained or lost any electron.

It is correct to say chlorine has 17 electrons and they occupy 3 electronic shells.

Answer:

Has 17 electrons.

Explanation:

I got this right on a test.

He taught about That matter was made up of atoms

~Hope that helped!

~Izzy  

Robert Boyle taught inverse relationship between volume and pressure of gases also known as pressure law in 1600s.

In 1600s Robert Boyle taught his law of inverse relationship between volume and pressure of gases.

Robert Boyle states that at a fixed mass of a gas and constant temperature, the pressure of the gas is inversely proportional to its volume.

The law is written as follows;

P₁V₁ = P₂V₂

where;

Thus, we can conclude that Robert Boyle taught inverse relationship between volume and pressure of gases also known as pressure law in 1600s.

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the answer for your question is B. Electromagnetic. because electric charge is the physical property that causes it to experience force when it is placed in a electromagnetic field the electric charge is carried by subatomic particles which causes the movement of the magnetic force

It’s (B) as Electromagnetic force.

Non-contact forces are those which act on an object without any physical contact with that object. The electromagnetic force is responsible for the interaction between electrically charged particles. So when electric charges move they produce the electromagnetic field in their surroundings. These fields act as the electromagnetic force for the other charged particles or object present within its sphere.

Compounds K3PO4  and MgCl2  are soluble in water , as phosphates of alkali metal cations are soluble in water and chlorides  Of Mg²⁺ are soluble in water . So , they dissociate into ions.

Ions K⁺ and  Cl⁻ combine to form  KCl  , soluble compound.

Ions PO₄³⁻  and Mg²⁺ combine to  form Mg3(PO4)2 ,  a precipitate  as phosfates of Mg²⁺ are insoluble  in water

Thus , the balanced equation , is:

2 K3PO4(aq) + 3  MgCl2(aq ) ----------->  6 KCl(aq)  + Mg(PO4)2(s)

The reaction of K3PO4 and MgCl2 in an aqueous solution results in potassium chloride and magnesium phosphate through ion exchange. This reaction is balanced according to the principle of conservation of matter, yielding the balanced chemical equation: 2K3PO4(aq) + 3MgCl2(aq) -> 6KCl(aq) + Mg3(PO4)2(s).

The perception reaction requested involves the substances K3PO4 (Potassium Phosphate) and MgCl2 (Magnesium Chloride). Both are present in an aqueous solution, denoted by (aq). We start the reaction with these compounds: K3PO4(aq) + MgCl2(aq).

To complete the reaction, we exchange the ions of the compounds. Potassium will bind with Chlorine and Magnesium will bind with Phosphate. This gives us: 2KCl(aq) + Mg3(PO4)2(s).

Finally, we balance the resulting equation to align with the law of conservation of matter. This ensures the amount of each atom type is the same both before and after the reaction. The balanced equation becomes: 2K3PO4(aq) + 3MgCl2(aq) -> 6KCl(aq) + Mg3(PO4)2(s).

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Hey there!:

Mass = 14.7 g

Volume = 2.2 cm³

Density = ?

Therefore:

D = m / V

D = 14.7 / 2.2

D = 6.67 g/cm³

Answer J

Hope that helps!

By definition of density,  the correct answer is option J: the density of the mineral sample is 6.7 [tex]\frac{g}{cm^{3} }[/tex].

In first place, you have to know that density is defined as the property that matter, whether solid, liquid or gas, has to compress into a given space. In other words, density is an intensive property of matter defined as the ratio of an object's mass to its volume.

For its calculation, the density is defined as the quotient between the mass of a body and the volume that  occupies:

[tex]density=\frac{mass}{volume}[/tex]

In this way, substances with a higher density have a greater quantity of matter in a certain volume than substances with a lower density.

In this case, you know:

Replacing in the definition of density:

[tex]density=\frac{14.7 g}{2.2 cm^{3} }[/tex]

Solving:

density= 6.7 [tex]\frac{g}{cm^{3} }[/tex]

In summary, the correct answer is option J: the density of the mineral sample is 6.7 [tex]\frac{g}{cm^{3} }[/tex].

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Even though our planet has a lot of water, some areas don't experience rain much and they aren't close to large bodies of water.

So in those areas they don't get to drink much water, because there isn't much available.

We may have a unlimited supply of water, but in other countries they might not. Hot, humid area's that don't experience rain won't have any water to drink, so they go to extreme measures and drink from cactus, or eat cactus fruit.

Also, most of the water on earth isn't drinkable which can cause sickness.

Answer:

Conceptual model - a diagram that shows the shape of the magnetic field around an object

Physical model - several balls and sticks glued together to represent a molecule

Virtual model - a computer program that shows all possible planetary orbits

Mathematical model - an equation that shows how an object’s acceleration relates to its mass

Explanation:

happy to help :^)

The correct pairings of conceptual models with their corresponding examples:

A physical model is a copy or imitation of something that helps us see and understand its features, how it behaves, or its design. Physical models are objects that you can touch and are in three dimensions. They can be similar to a smaller version of a building or simple objects like balls and sticks that represent molecules.

A virtual or computer-made picture  of something that you can use to study and interact with. Virtual models are frequently used in simulations and computer programs to imitate real-life events or situations. An example is a computer program that displays how planets move in their paths around the sun.

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Answer:

Please see the attached picture.

Explanation:

For subshell s, there is only 1 orbital hence 1 square is drawn. For subshell d, there are 5 orbitals hence 5 squares are drawn.

Period is the row number in the periodic table.

Note that there are some deviations from the aufbau principle (Electrons fill orbits of lowest sub energy level to capacity before filling orbitals of higher sub energy levels). For the first row of transition elements, chromium and copper deviate from Aufbau principle. Hence their electronic configuration does not follow the format.

The orbital diagram for Scandium is [Ar]  [tex]3d^1 4s^2[/tex]

Scandium has an atomic number of 21, so it has 21 electrons. The electron configuration for Scandium is:

[tex]1s^2 2s^2 2p^6 3s^2 3p^6 3d^1 4s^2[/tex]

The orbital diagram shows how the electrons are arranged in the orbitals of the atom. The 1s orbital is the lowest energy orbital, and the 4s orbital is the highest energy orbital. The 3d orbital is filled with one electron, and the 4s orbital is filled with two electrons.

The orbital diagram for Scandium shows that it is a transition metal. Transition metals have partially filled d orbitals. This gives them the ability to form a variety of chemical bonds, which is why they are so versatile in their applications.

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Answer:

The weight of the object on earth =441N

Weight of the object on moon = 72N

Explanation:

Weight of a body is the product of its mass and acceleration due to gravity. Acceleration due to gravity varies between planetary bodies. The acceleration due to gravity on earth is 9.8 m/s² while on moon is 1.6m/s² and it goes different for others too.

Weight = Mass * acceleration due to gravity

Weight(e) = weight on earth

Weight (m) = weight on moon

Weight(e) = 45 * 9.8 = 441N

Weight (m) = 45 * 1.6 = 72N

Weight of a body is measured in a unit called Newton(N)

The weight of a 45-kilogram object on Earth is 441 newtons, on the Moon the object's weight is 72 newtons. Weight varies by location due to the differences in gravitational force.

The weight of an object is calculated by multiplying the object's mass by the gravitational force. The standard formula to calculate weight is w=mg where 'w' represents weight, 'm' is mass, and 'g' is the acceleration due to gravity. On earth, the gravitational force is about 9.8 m/s², while on the moon this force dramatically decreases to about 1.6 m/s².

Using this formula, we can calculate the weight of an object with a mass of 45 kilograms on Earth and the Moon. On earth, the weight would be 45 kg x 9.8 m/s² which gives us a result of 441 newtons. While on the moon, the weight would be 45 kg x 1.6 m/s², resulting in 72 newtons.

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Answer: 197 grams

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar Mass}}=[/tex]

Given mass = 405 g

Molar mass = 78.07 g/mol

[tex]\text{Number of moles}=\frac{405g}{78.07g/mol}=5.19moles[/tex]

1 mole of [tex]CaF_2[/tex] contains = 2 moles of fluorine

5.19  mole of [tex]CaF_2[/tex] contains = [tex]\frac{2}{1}\times 5.19=10.38moles[/tex] of fluorine

Mass of flourine =[tex]moles\times molar mass=10.38\times 19=197g[/tex]

Thus 197 grams of F are in 405 grams of [tex]CaF_2[/tex] .

Ions are electrically charged particles, meaning, that whenever any type of atom loses or gains electrons it is forming a new type of structure, or ion.

Metal atoms form postive ions, Non-Metals form negative ions.

The strongest type of bond that can occur between two ions, when they are oppositely charged, are Ionic Bonds. The most commonly known ionic bond is seen in Sodium and Chlorine, which when combined give us NaCl or Sodium Chlorine, aka Salt.

+1 charge = Group 1, Metals

+2 charge = Group 2, Alkali Metals

-1 charge = Group 17, Halogens

Provided is a periodic table marked with the charges for each group.

In the reaction H2SO4 + H2O → H3O+ + HSO4− the Bronsted-Lowry acid is H2SO4, which donates a proton to H2O to form H3O+ and its conjugate base HSO4−.

In the forward reaction H2SO4 + H2O → H3O+ + HSO4-, the substance acting as the Bronsted-Lowry acid is H2SO4. According to the Bronsted-Lowry definition, an acid is a substance that can donate a proton (a hydrogen ion) to another substance.in this case, H2SO4 donates a proton to H2O, forming H3O+ (the hydronium ion) and its conjugate base HSO4-. Thus, the Bronsted-Lowry acid in this reaction is H2SO4.

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C. Sulfur

Is the answer.

your answer is sulfur because the atomic number is the same as protons!

plz mark as brainliest

Answer:

223

Explanation:

I had the same problem and put 223, it was correct.

Answer:

A battery that produces electricity

Explanation:

Galvanic cell is a battery which converts chemical energy to electrical energy.

In galvanic cell two half cells work, one is cathodic and other is anodic.

At cathode reduction takes place and at anode oxidation takes place.

Due to this redox reaction some voltage is generated which is known as emf of the cell.

The EMF of the cell calculated from the difference of reduction potential of cathode and anode.

The cell will work if the emf of the cell is positive.

If emf of the cell is positive it means that cell is spontaneous,

Free energy change = ΔG°= -nFE°

thus a positive values of E° corresponds to negative value of ΔG°, and hence a spontaneous reaction.

Where E° is emf of the cell

Hey there!

A neutron is found in the nucleus of an atom. All neutrons have a neutral charge while protons have a positive charge, and electrons have a negative charge.

I hope this helps! Have a sparking day!

A neutron has no charge and is electrically neutral.

The neutron is an electrically neutral subatomic particle with no charge. It is neither positively charged nor negatively charged.

This makes it different from the proton, which carries a positive charge, and the electron, which carries a negative charge.

Neutrons are found in the nucleus of an atom along with protons.

Their mass is slightly greater than that of a proton.

For example, the neutron has a mass of 1.0087 atomic mass units (amu) while the proton has a mass of 1.0073 amu.